Deployment of conductors into the atmosphere

ABSTRACT

A system for rapidly deploying long, electrically conducting filaments of metallized Mylar in the air at selected altitudes by winding the Mylar in tight rolls and loading the rolls into small rocket pods in the nose of a folding fin aircraft rocket. The rolls are pyrotechnically ejected by causing the pod to fly apart and allow the tape rolls to enter the air stream and unwind.

United States Patent 91 Whidden et al.

1451 Oct. 7, 1975 1 DEPLOYMENT OF CONDUCTORS INTO THE ATMOSPHERE [75] Inventors: Roger W. Whidden, Dedham; Frank R. Leonard, Billerica; Sidney Rosenthal, West Newton; Richard O. Fitzpatrick, Fitchburg, all of Mass.

[73] Assignee: The United States of America as represented by the Secretary of the Air Force, Washington, DC.

[22] Filed: Mar. 25, 1974 [21] Appl. No.: 454,199

[52] US. Cl. l02/34.4; 102/49.4; 102/63; 102/89; 343/18 B [51] Int. Cl. F42B 13/28 [58] Field of Search 102/34.4, 35.6, 37.6, 49.4, 102/49.5, 63, 89; 343/18 B [56] References Cited UNITED STATES PATENTS 2,463,233 3/1949 Alexanderson 343/18 B Primary Examiner-Verlin R. Pendegrass Attorney, Agent, or Firm-Joseph E. Rusz; Arsen Tashjian [57] ABSTRACT A system for rapidly deploying long, electrically conducting filaments of metallized Mylar in the air at seiected altitudes by winding the Mylar in tight rolls and loading the rolls into small rocket pods in the nose of a folding fin aircraft rocket. The rolls are pyrotechnically ejected by causing the pod to fly apart and allow the tape rolls to enter the air stream and unwind.

3 Claims, 2 Drawing Figures DEPLOYMENT OF CONDUCTORS INTO THE ATMOSPHERE BACKGROUND OF THE INVENTION This invention relates to a system for deploying long electrically conducting filaments of metallized material in the air and, more particularly, the invention is concerned with pyrotechnically ejecting a tightly wound roll of tape into the atmosphere at a predetermined altitude such that the aerodynamic forces cause deceleration and initiate unwinding at a no-destructive rate.

It has been demonstrated that lightning from overhead thunderstorms would strike a long, rapidly rising, grounded conductor, specifically a thin wire towed by a miniature rocket. The powerful engines of large space vehicles leave trails of ionized gases, which may also act as extended conductors and attract lightning under certain meteorological conditions. This is believed to have been the case with Apollo 12 in November 1969, when the vehicle suffered a cloud-to-ground stroke near 6000 ft altitude, and a cloud-type discharge around 14,400 ft. It would be useful for simulation and other purposes to have a convenient, inexpensive technique for deploying test conductors at this, and preferably higher, altitudes.

Wires have been successfully deployed from canisters dropped from aircraft and they could no doubt also be deployed from balloons, but neither technique offers the fundamental advantage of rockets (or shells from guns); namely, the possibility of quickly position ing conductors in a designated volume of the atmosphere as may be desired by ground experimenters. For this application, rockets having a short burn and hence essentially ballistic trajectories are preferred over those having extended periods of powered thrust and hence a greater chance of becoming misdirected in the turbulent air frequently associated with thunderstorms. The conductor must therefore be packaged ruggedly to withstand high-acceleration launches, as well as the deceleration after release into the air.

SUMMARY OF THE INVENTION The present invention provides a system for packaging, ejecting and deploying 1000 foot lengths of metallized Mylar tape or the like from small, high-g rockets. Heat from the rocket motor raises the temperature of the chamber wall sufficiently to ignite a fuze which subsequently ignites a small powder charge, causing a piston to move forward against two staves which press against the cap of the rocket pod pushing it clear of the pod. The cylindrical section of the pod is made up of two separate sections or shells which fly apart and hinge backward shearing off thereby releasing the tape rolls which enter the air stream, decelerate and begin to unwind.

Accordingly, it is an object of the invention to provide a technique for modifying electrical activity in the atmosphere to reduce the hazards of lightning strokes especially during missile launching operations.

Another object of the invention is to provide a system for deploying long conductors of material, such as Mylar tape, into the atmosphere. This is accomplished by launching and unwinding at a now-destructive rate so that the severe mechanical and aerodynamic forces encountered do not damage the tapes.

Still another object of the invention is to provide a system for deploying a long conductor into the atmosphere by ejecting a specially wound roll of tape which is housed in a clam shell actuated nose cone of a rocket. The heat of the rocket motor ignites a fuse which expands a powder charge causing the clam shell housing to split and release the rolls of tape.

A further object of the invention is to provide a system for rapidly deploying long, electrically conducting filaments of metallized Mylar in the air at selected a1titudes by installing specially wound rolls into a-small rocket pod and pyrotechnically ejecting them at a predetermined altitude. Aerodynamic forces decelerate the rolls and cause them to unfurl rapidly.

These and other objects, features, and advantages will become more apparent after considering the following description taken in conjunction with the annexed drawing and appended claims.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in cross section of the rocket nose assembly showing the rocket pod with the tightly wound Mylar tape disposed in the nose portion thereof; and

FIG. 2 is a partially sectioned view showing the details of the pyrotechnic pod opener which fits behind the wound tape rolls.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, there is shown the forward portion 13 of a conventional folding fin aircraft rocket (FFAR) which has an apogee in the order of 15,000 to 20,000 ft. when fired from a suitable ground launcher. While this altitude is considerably below many thunderclouds, the FFAR was useful for test purposes. A typical F FAR. for deploying tapes may be 2.75 inches in diameter with the motor section 39.4 inches long and weighing about 1 1.0 pounds at launch and 5.1 pounds at burnout. The maximum thrust is nominally 720 pounds, and with a nominal payload of 3 pounds, the maximum acceleration is in the order of 50 g.

A pod 15 is positioned on the forwardmost portion of the FFAR l3 and includes the pod cap 17 and the pod shells 19 which are hingedly attached to the forward portion 13 of the FFAR by means of the pins 21. A plurality of staves 23 are disposed immediately adjacent the inner wall of the pod shells 19. A piston 25 is positioned in the rearwardmost end of the pod 15 in contact with the rearward end. of the staves 23.

A pyrotechnic pod opener 27 shown in detail in FIG. 2 is positioned directly behind. the piston 25. The pod opener 27 includes a grooved spindle 29 around which a powder fuse 31 is wound. A typical composition of the fuse 31 has 15 grams/foot powder core and is 0.1 15 inches outside diameter having a delay of seconds per yard. The forward end of the fuse 31 is embedded in a powder charge 33 composed of, for example, Dupont lMR-4l98, which is capped with plug-wadding 35 press fit into the forward end of the pod opener 27. The rearward end of the fuse 31 is attached to the forward chamber wall 37 of the rocket motor and passes through the center portion of the pod opener 27 and emerges through an opening in one of the grooves in the spindle 29. Two tape rolls 39 are positioned in the pod 15 within the pod shells 19.

MODE OF OPERATION In operation, the tape rolls 39 are housed in the metal pod 15 for protection until the programmed moment of ejection. The altitude of ejection is controlled by a py' rotechnic time-sequence which begins just after rocket ignition. Heat from the motor raises the temperature of the chamber wall 37 sufficiently to ignite the end of the powder fuse 31 which is in contact with it. After a delay determined by the length of the fuse 31 would on the grooved spindle 29, the fuse 31 ignites the small powder charge 33. The piston is forced forward against the two staves 23 pressing them against the pod cap 17, which is pushed clear of the pod 15. The cylindrical section of the pod 15 which consists of two separate pod shells 19 originally was held together by the cap 17. Removal of the cap 17 allows the shells 19 to fly apart hinging back about the pins 21, which then shear off leaving the rocket casing flat-nosed. The tape rolls 39 enter the air stream, decelerate, and begin to unwind. A suitable tape for winding the tape rolls 39 would be Mylar tape base 0.025 mm thick and 6.5 mm wide. An aluminum coating nominally 2 to 3 angstroms thick gives a conductivity of about 230 ohms/meter. The breaking strength of this tape is about 6.8 kg and under static conditions its breaking strength is km.

Although the invention has been illustrated in the accompanying drawing and described in the foregoing specification in terms of a preferred embodiment thereof, the invention is not limited to this embodiment or to the particular configuration mentioned. It will be apparent to those skilled in the art that our system for deploying 1000 foot long electrically conducting filaments into the atmosphere could have extensive use in other operations where it is desired to reduce the hazards of lightning strokes, such as during in-flight refueling of high flying aircraft, by discharging the lightning through the filaments.

Having thus set forth and disclosed the nature of our invention, what we claim and desire to secure by Letters Patent of the US. is:

1.. Apparatus for deploying a long electrical conductor into the atmosphere from an aircraft rocket or the like comprising a pod positioned on the forward end of the rocket and holding a ball of tape, said pod including a pair of pod shells of complementary semi-cylindrical configuration hingedly attached to said aircraft rocket and a pod cap slidably attached to the forwardmost portion of said pod shells and operating to maintain pod shells in closed position, a pyrotechnic pod opener positioned in said rocket immediately behind said pod, and means for opening said pod and releasing its contents after passage of a predetermined controllable time interval by activating said pyrotechnic pod opener when the motor in said rocket reaches a predetermined temperature level.

2. The apparatus for deploying a long electrical conductor into the atmosphere defined in claim 1 wherein said pod opener includes a grooved spindle, a powder charge in the forward end of said spindle, a powder fuse disposed in the grooves of said grooved Spindle, the forward end of said fuse being embedded in said powder charge and the rearward end of said fuse being in contact with the forward wall of the motor of the aircraft rocket.

3. The apparatus for deploying a long electrical conductor into the atmosphere defined in claim 2 wherein said means for opening said pod includes a piston slidably positioned in the rearward end of said pod, a pair of staves disposed between the forward face of said piston and the base of the pod cap, said staves being slidably positioned against the inner wall of the pod shells such that the powder charge of said grooved spindle is in contact with the rearward face of said piston and the burning of the powder charge forces the piston forward against the staves forcing the pod cap away from the pod shells allowing them to open and release the contents thereof. 

1. Apparatus for deploying a long electrical conductor into the atmosphere from an aircraft rocket or the like comprising a pod positioned on the forward end of the rocket and holding a ball of tape, said pod including a pair of pod shells of complementary semi-cylindrical configuration hingedly attached to said aircraft rocket and a pod cap slidably attached to the forwardmost portion of said pod shells and operating to maintain pod shells in closed position, a pyrotechnic pod opener positioned in said rocket immediately behind said pod, and means for opening said pod and releasing its contents after passage of a predetermined controllable time interval by activating said pyrotechnic pod opener when the motor in said rocket reaches a predetermined temperature level.
 2. The apparatus for deploying a long electrical conductor into the atmosphere defined in claim 1 wherein said pod opener includes a grooved spindle, a powder charge in the forward end of said spindle, a powder fuse disposed in the grooves of said grooved spindle, the forward end of said fuse being embedded in said powder charge and the rearward end of said fuse being in contact with the forward wall of the motor of the aircraft rocket.
 3. The apparatus for deploying a long electrical conductor into the atmosphere defined in claim 2 wherein said means for opening said pod includes a piston slidably positioned in the rearward end of said pod, a pair of staves disposed between the forward face of said piston and the base of the pod cap, said staves being slidably positioned against the inner wall of the pod shells such that the powder charge of said grooved spindle is in contact with the rearward face of said piston and the burning of the powder charge forces the piston forward against the staves forcing the pod cap away from the pod shells allowing them to open and release the contents thereof. 